USB-KW019032 Freescale USB Dongle Development Board , User’s Guide, Rev. 0, 10/2015
Freescale Semiconductor, Inc.
11
USB-KW019032 development board
4.2.2
Clocks
The USB-KW019032 board provides one clock (a 32 MHz reference oscillator).
Figure 7
shows the
32 MHz external crystal Y1. This mounted crystal meets the MKW01Z128 transceiver requirements.
— Capacitors C22 and C21 provide the bulk of the crystal load capacitance. At 25 °C, it must have
the frequency accurate to ±10 ppm (or less) to enable temperature variation.
— Signal DIO5/CLKOUT can be used to supply an external clock to the MCU die.
Figure 7. USB-KW019032 32 MHz reference oscillator circuit
4.2.3
Power management
There is a single way to power the USB-KW019032 board. It is made via the type-A USB connector J5 to
supply 5 V (VUSB) directly to the secondary MCU (MK22FN512), which includes an internal LDO and
a 3.3 V output to enable the MKW01Z128 device. The USB-KW019032 power management circuit is
shown in
Figure 8
.
